A new formula that allows the first natural frequency of transverse vibrations of axially loaded steel helical springs to be determined has been presented in the paper. The relationship is easy to use and allows finding the first natural frequency of spring vibrations without the necessity of...

The objective of this paper is to present a new approach to the problem of combustion engine efficiency characteristic development in dynamic working states. The artificial neural network (ANN) method was used to build a mathematical model of the engine comprising the following parameters: Engine speed, angular acceleration, engine torque, torque change intensity, and fuel mass flow, measured on a test bed on a spark ignition engine in static and dynamic working states. A detailed analysis of ANN design, data preparation, the training method, and the ANN model accuracy are described. The paper presents conducted calculations that clearly show the suitability of the approach in every aspect. Then, a simplified ANN was created, which allows a two dimensional characteristic in dynamic states, including 4 variables, to be determined.

The article presents the influence of number and values of ratios in stepped gearbox on mileage fuel consumption in a city passenger car. The simulations were conducted for a particular vehicle characterized by its mass, body shape, size of tires and equipped with a combustion engine for which the characteristic of fuel consumption in dynamic states was already designated on the basis of engine test bed measurements. Several designs of transmission with different number of gears and their ratios were used in virtual simulations of road traffic, particularly in the NEDC test, to calculate mileage fuel consumption. This allows for a quantitative assessment of transmission parameters in terms of both vehicle economy and dynamic properties. Also, based on obtained results, recommendations for the selection of a particular vehicle for a specific type of exploitation have been formulated.

Torque is the fundamental working parameter of the internal combustion engine (ICE). In a spark ignition (SI) ICE, static torque is a function of rotational speed and throttle angle. However, ICE inertia, the distance between the throttle and cylinders, the time interval between subsequent intake strokes and increased oil viscosity in the warm-up phase limit the use of this characteristic in dynamic states. The novel and simple formula for calculating ICE torque in dynamic working states, presented in the article, includes all the mentioned factors. The new formula is based on ICE static tests where the torque, speed, throttle angle and airflow are measured. On the basis of the intake manifold geometry, the phenomena occurring in this component are described to determine the delay in the ICE response to throttle position changes. Moreover, the influence of ICE inertia is included. Finally, the formula includes the ICE warm-up period, which is characterized by high friction losses that decrease ICE torque. The proposed formula is validated by comparing model performance in dynamic working states with measurements. The results show a high level of accuracy: the delay in ICE response differs by less than 0.01 s, and the calculated torque differs by less than 5%.

The aim of this paper is to present mathematical models of all the propulsion components of hybrid drivetrains. These models are based on very limited amounts of data, nevertheless they match real characteristics with high accuracy based on numerous measurement data points, thus they allow the...